<!DOCTYPE html>
<head>
    <script>
        var a = 2;
        document.write(a+2 +"<br>");
        var b = 3;
        document.write(a*b +"<br>");
        b +=1;
        document.write(b + "<br>");
        document.write(b/a + "<br>");
        document.write(b%a + "<br>");
        var n1 = 1;
        var n2 = 2;
        console.log(n1 == n2);
        var t1 = 123;
        var t2 = "123";
        console.log(t1 == t2);
        console.log(t1 === t2);
           
        var score = 5;
        if (score > 90) {
            console.log("优秀");
        } else if(score > 70){
            console.log("良好");    
        } else if(score > 60) {
            console.log("及格");
            } else {
            console.log("不及格");
            }

        var day = 8;
        switch(day){
            case 1 : console.log("周一");
            break;
            case 2 : console.log("周二");
            break;
            case 3 : console.log("周三");
            break;
            case 4 : console.log("周四");
            break;
            case 5 : console.log("周五");
            break;
            case 6 : console.log("周六");
            break;
            case 7 : console.log("周日");
            break;
            default : console.log("请输入1-7之间的数字");
            break;

        }

        for(var i = 1; i < 4; i++){
            console.log(i)
        }
        console.log("i=" + i);
        var e = 1
        while(e<4){
            console.log(e);
            e++;
        }
        var r =1;
        do {
            console.log
        } while (condition);


        
   
         

        

    </script>   
</head>